The study of arterial fluid dynamics has been revolutionized with theintroduction of supercomputers and recent advances in the field of computational fluid dynamics(CFD). Our current research is aimed at investigating the hemodynamics of intracranial arterial blood flow and its role in the formation of saccular "Berry" aneurysms. Our work suggests that high pressures arise 1) at the apex of arterial bifurcations and 2) along the outer wall of curved arteries. It is our opinion that these stress concentrations are primarily responsible for the initiation and growth of saccular aneurysm at these sites within the cerebral circulation . Current finite element(FE) models are limited in that they are 2-D and assume a rigid arterial wall. We are now using MRI/CT imaging data from actual patients to construct true, 3-D FE models of intracranial arteries and aneurysms. Since a typical 3-D mesh requires on the order of 10+(5)-10+(6) nodes, computers with high-speed parallel processors are necessary to solve the complicated set of nonlinear partial differential equations(Navier-Stokes) describing the velocities and pressures that arise at each node. It is our goal to develop a 3-D, elastic-wall model of intracranial arterial blood flow and aneurysm formation. This will involve coupling the fluid dynamic equations with those describing the solid mechanics of the arterial wall. We also plan to construct computational models to assess the effects of various medical/surgical therapies in the treatment of saccular aneurysms(e.g., antihypertensive agents, aneurysm clipping, and endovascular coil placement). FIDAP will be used to test 3-D rigid-wall models. Spectrum and ADINA will be used to incorporate the elastic properties of the arterial wall. Both packages are capable of simulating the multiple, interacting physics of pulsatile blood flow and the arterial wall(fluid-structure interaction).